This invention relates to cleansing compositions for human use and more particularly to a cleansing composition in solid or bar form which is highly transparent, of exceptional mildness, and which will accept and is compatible with a variety of skin benefiting additions such as sunscreens, proteins, emollients and the like without adversely affecting the clarity of the composition.
Translucent or substantially transparent soap bars have been available for consumer use for a number of years. These soap bars are generally glycerine-based or alcohol-based to obtain the desired clarity and contain high levels of sodium and/or potassium stearate, usually 65 percent or more, and when dissolved in water exhibit alkaline pH""s of 8.5 or more and usually at least 9.5. These soaps have been said to be substantially less irritating than conventional non-translucent or non-transparent soap bars which contain from 65 to 95 percent sodium stearate and exhibit alkaline pH""s ranging from 9.5 to 10.0. However, even the glycerine-based soap bars of pH""s in the area of 9.5 or more have been found to be irritating to the skin and undesirable for use by those having particularly sensitive skin.
It has also been found that glycerine-based soap bars exhibit relatively high hygroscopic tendencies, that is they absorb water on the surface, which causes the bar""s surface to slough and become scaly.
With respect to the alcohol-based soap bars, it has been found that alcohol evaporates from the bar over relatively short periods of time, thereby causing a reduction in size and clarity of the bar. The loss of alcohol may also cause the soap bar to become rubbery.
In formulating transparent soap, a classic method involves the low temperature saponification of fats and oils predissolved in warm alcohol, water and glycerine, followed by evaporation of part of the alcohol/water azeotrope. Another common technique is based upon the addition of a polyhydric alcohol, such as glycerol, glycol, sugar or the like to a xe2x80x9cneat soapxe2x80x9d or semi-boiled soap, or to soap prepared by the cold process technique. Still another method consists of dissolving soap in alcohol to solubilize certain components and then distilling off most of the alcohol.
U.S. Pat. No. 3,562,167 to Kamen describes a transparent soap formed from a combination of soap, polyhydric alcohol and, as a surface-active agent, a polyalkoxy ether of an alkylphenol.
U.S. Pat. No. 3,903,008 to Deweever et al describes the formulation of a transparent soap by the combination of soap, polyhydric alcohols and a quaternized dihydroimidazole detergent.
U.S. Pat. Nos. 3,793,214 and 3,926,828 to O""Neil et al describes transparent soaps produced using branched chain fatty acids. U.S. Pat. No. 3,864,272 to Toma et al, describes the use of a rather elaborate mechanical method of working the soap, i.e., spray drying followed by mechanical working to effect transparency.
A method of formulating a transparent soap is disclosed in U.S. Pat. No. 2,820,768 where a sodium soap made from tallow, coconut oil and castor oil is mixed with a triethanolamine soap of stearic acid, an oleic acid and an excess of the amine.
U.S. Pat. No. 4,290,904 describes a transparent low alkalinity bar soap based on a tetrakis (hydroxyalkyl)ethylene diamine.
U.S. Pat. No. 4,165,293 to Gordon discloses a solid transparent soap utilizing a high sodium soap content (about 55%) with a dihydric alcohol along with the anionic or amphoteric surfactant.
U.S. Pat. No. 4,719,030 to Williams et al describes a transparent soap bar using a water-insoluble synthetic amorphous silica or silicate having a specific surface area.
U.S. Pat. No. 4,851,147 to Esposito et al discloses a transparent soap using certain alkyl-aryl polyoxyalkalene carboxylic acids, a synthetic detergent, benzoic acid esters of primary alcohols and fatty acid soap.
A disadvantage of many of the early prior art transparent soap bars is that they form the typical scum in hard water. In order to overcome this problem with soaps in general, not only in transparent soaps, synthetic detergents were developed. It has been found, however, that when these synthetic detergents were added to the typical transparent soap to form what is called a xe2x80x9ccombo-barxe2x80x9d (i.e., a combination of synthetic detergent and soap), transparency is a problem. To our knowledge, no one to date has made a transparent bar using a synthetic detergent and a soap having the enhanced transparency, clarity, and mildness described and claimed herein.